1. Technical Field
The present invention is directed to power transmission belts, and in particular, to power transmission belts having a laminar construction.
2. Background Art
It is known in the art to fabricate power transmission belts for automobile engines by embedding load carrying cords in a layer of chloroprene rubber. This method and these materials have been used to fabricate power transmission belts for use in the automobile industry for many years.
However, modem automobile engines are designed to operate at higher temperatures and at higher speeds than older automobile engines. As a consequence, demands are being put on the power transmission belts for these engines that cannot be met using the standard chloroprene rubber construction. Chloroprene rubber is known to cure easily in a high temperature environment, such as is found in a modern automobile engine compartment. This curing of the chloroprene rubber may lead to premature cracking in the belt, which may ultimately lead to premature belt failure.
Additionally, in such a high temperatures environment, chloroprene rubber has been known to fail to adequately adhere to the load carrying cords embedded therein. As a result, the chloroprene rubber may "peel" off the load carrying cords, causing the cords to "pop out", thereby potentially reducing the transmission belt life and leading to premature belt failure.
Moreover, transmission belts made from chloroprene rubber may not be able to withstand the side pressures exerted on the transmission belts by the pulleys into which the belt is fitted. The poor resistance to side pressure may result in a buckling deformation of the belt known as dishing. Dishing can make it impossible to effectively transmit power through the belt.
Many alternative materials have been tried in the art as alternatives to chloroprene rubber. For example, Japanese Laid Open Application No. 271,472/1993 discloses an alternative material formulated from a hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt, such as zinc methylacrylate. Japanese Laid Open Application No. 311,158/1989 discloses a second, alternative material formulated from a hydrogenated nitrile rubber or a rubber composition obtained by mixing a hydrogenated nitrile rubber with an unsaturated carboxylic acid metal salt, such as zinc methacrylate, for example, and an organic peroxide.
The material disclosed in Japanese Laid Open Application No. 271,472/1993 may still experience a high degree of "pop out" because of the hardness of the rubber. Additionally, the material may not exhibit sufficient resistance to side pressure when the material is placed in compression.
The material disclosed in Japanese Laid Open Application No. 311,158/1989 may not permit the practical use of conventional reinforcing and strengthening materials, such as carbon black and short fibers. In fact, use of carbon block and short fibers may actually decrease the strength of the rubber. Moreover, without some type of reinforcement, the disclosed material may not exhibit sufficient resistance to side pressures, or to flexing fatigue.
The present invention is directed toward overcoming one or more of the problems discussed above.